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Wisconsin S14D Engine

The Wisconsin S14D is a heavy-duty, industrial-grade, single-cylinder, four-cycle gasoline engine manufactured by Wisconsin Motors. Engineered for severe-duty applications such as garden tractors (e.g., the Bolens 1455), log splitters, and industrial machinery, this engine is recognized for its robust cast-iron construction and high torque output. It features an automatic compression release integrated directly into the camshaft assembly to prevent starting kick-back and minimize operator effort. The crankshaft rotates clockwise when viewed from the flywheel/starting end, yielding a counter-clockwise rotation at the power take-off (PTO) end. Due to its heavy component build, the cylinder block is designed to be rebored and fitted with oversize pistons and rings during overhauls to ensure extreme longevity.

The engine employs a side-valve (L-head) mechanical layout featuring non-interchangeable intake and exhaust valve assemblies housed within the cylinder block. The valvetrain utilizes dedicated valve stem guides, spring seats, retainer locks, and hardened valve seat inserts for both the inlet and exhaust ports. Bore Diameter: 3.75 inches (3-3/4 inches / 95 mm). Stroke Length: 3.00 inches (3 inches / 76 mm). Total Displacement: 33.1 cubic inches (542 cc). The engine utilizes a forced-air cooling design. Air circulation is generated by a combination fan-flywheel component encased inside a structured sheet-metal blower shroud. The forced air stream is split and precisely directed over the cylinder block cooling fins and cylinder head by integrated air ducts and internal baffle plates to guarantee uniform heat dissipation.

The fuel system is designed to run exclusively on regular-grade gasoline with a minimum rating of 87 octane. The standard setup relies on a side-draft or up-draft carburetor configuration, typically utilizing factory-installed Zenith or Walbro carburetors (such as the Zenith 1408 or Walbro LMH series). Atmospheric filtration is handled by a dry-element style air cleaner assembly mounted directly to the carburetor intake horn. Fuel delivery from the main fuel tank is managed via gravity feed or a mechanical fuel pump assembly, such as the LP-62 repairable fuel pump. Lubrication is managed via an internal splash and dip distribution network driven by the moving internal components inside the crankcase.

General Technical Data

Engine Specifications

Engine Model ............... Wisconsin S14D
Engine Manufacturer ............... Wisconsin Motors LLC
Engine Configuration ............... Single-cylinder horizontal-shaft heavy-duty industrial
Operating Cycle ............... 4-cycle spark-ignition internal combustion
Cooling Classification ............... Forced-air cooled via high-efficiency flywheel blower
Number of Cylinders ............... 1
Cylinder Bore Diameter, in (mm) ............... 3.750 (95.250)
Piston Stroke Length, in (mm) ............... 3.000 (76.200)
Total Displacement, cu.in (cc) ............... 33.10 (542.40)
Rated Power, hp (kW) ............... 14.00 (10.44) at 3600 rpm
Continuous Power, hp (kW) ............... 11.90 (8.87) at 3600 rpm
Maximum Torque, lb-ft (Nm) ............... 25.50 (34.57) at 2400 rpm
Operating Speed, rpm ............... 3600
Idle Speed, rpm ............... 1000-1200
Compression Ratio ............... 6.5:1
Engine Rotation Direction ............... Counterclockwise viewed from power take-off shaft side
Cylinder Block Material ............... High-tensile cast iron with integral cooling fins
Cylinder Head Material ............... Removable aluminum alloy with optimal heat-dissipating deep fins
Crankcase Base Material ............... Cast iron heavy-duty structural sump mounting base
Camshaft Casting Design ............... Cast iron with precision-ground lobes and gear drive
Valves Config Arrangement ............... Side-valve design utilizing L-head structural configuration
Intake Valve Head Material ............... Premium heat-treated carbon steel alloy
Exhaust Valve Head Material ............... High-temperature resistant Stellite alloy face inserts
Valve Seat Inserts ............... Hardened alloy steel inserts pressed into cylinder block castings
Muffler Construction Type ............... High-volume steel canister reducing acoustic sound signatures
Flywheel Material Cast ............... High-density cast iron dynamic balanced with integrated fan blades
Lubrication Method ............... Splash system with positive mechanical oil pump distribution
Oil Pump Type ............... Camshaft-driven reciprocating plunger pump configuration
Oil Filter Type ............... Internal optional line strainer with screen filtration elements
Air Intake Filtration Type ............... Dry dual-stage element or optional heavy-duty oil bath setup
Ignition System ............... Flywheel magneto assembly or solid-state electronic module
Starting System ............... Electric starter motor with integrated flywheel ring gear
Electrical System, V ............... 12

Fuel System

Carburetor Manufacturer ............... Zenith Model 1408 or optional Walbro LMH unit
Carburetor Venturi Throat Size, in (mm) ............... 0.875 (22.225)
Carburetor Choke Mechanism ............... Manual cable-controlled butterfly valve with spring return
Carburetor Throttle Shaft Config ............... Hardened brass shaft with dual lip seal protection
Main Jet Specification ............... Adjustable needle valve variant providing fine load tuning
Idle Jet Control Method ............... Adjustable air-bleed screw modifying lower speed ratios
Fuel Delivery Pressure Level, psi (bar) ............... 1.50-3.50 (0.10-0.24)
Fuel Pump Config ............... Camshaft-actuated diaphragm style pump mounted to crankcase
Fuel Pump Repair Kit Reference ............... Wisconsin LP-62 service group standard package
Fuel Tank Total Capacity, gal (L) ............... 1.50 (5.68)
Optional Fuel Tank Capacity, gal (L) ............... 2.75 (10.41)
Governor Control ............... Mechanical flyweight type enclosed within internal gear train casing
Governor Regulation Percentage ............... 5-7 percent steady-state speed control regulation
Fuel Strainer Filter ............... Glass sediment bowl with integrated fine mesh screen element
Fuel Tank Drain Valve Assembly ............... Manual shut-off needle valve located at lowest point
Recommended Fuel Grade ............... Regular unleaded gasoline possessing minimum 90 rating
Fuel Tank Mounting Structure ............... Dual steel band clamps bolted onto upper air shroud brackets
Float Setting Level Dimension, in (mm) ............... 1.285 (32.639)
Float Needle Valve Seat Material ............... Hardened viton tip matching machined brass seating orifices
Idle Mixture Adjustment Setting ............... 1.25 turns open from seated stop index position
Main Needle Adjustment Initial Setting ............... 1.50 turns open from internal closed needle seat position
Governor to Throttle Linkage Design ............... Solid steel rod with internal anti-backlash tension spring
Choke Cable Outer Outer Diameter, in (mm) ............... 0.250 (6.350)
Carburetor Gasket Sealing Area ............... High-density composite paper preventing intake air bypass leaks
Intake Manifold Passage Diameter, in (mm) ............... 1.125 (28.575)
Intake Manifold Construction Type ............... Cast iron single piece bolted to cylinder side wall

Dimensions and Weight

Overall Engine Assembly Length, in (mm) ............... 18.5 (470)
Overall Engine Assembly Width, in (mm) ............... 19.3 (490)
Overall Engine Assembly Height, in (mm) ............... 21.8 (555)
Dry Weight (Standard Engine), lbs (kg) ............... 145 (65.7)
Dry Weight (Clutch Engine), lbs (kg) ............... 175 (79.5)
Dry Weight (Reduction Gear Unit), lbs (kg) ............... 185 (84)

Maintenance Data

Service Information

Spark Plug Reach, in (mm) ............... 0.750 (19.050)
Spark Plug Gap, in (mm) ............... 0.030 (0.762)
Breaker Point Gap, in (mm) ............... 0.020 (0.508)
Magneto Air Gap, in (mm) ............... 0.012-0.015 (0.305-0.381)
Ignition Timing ............... 20.000 deg BTDC
Intake Valve Clearance, Cold, in (mm) ............... 0.0070 (0.178)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.0160 (0.406)

Engine Oil

Engine Oil Type .................. SAE 30, SAE 20W, or SAE 10W
API Service Classifications ......................... MS, SD, SE, or SF
Crankcase Lubricating Oil Capacity, qt (L) ............... 1.50 (1.42)
Crankcase Oil Refill Capacity With Filter, qt (L) ............... 1.75 (1.66)
Reduction Gear Case Lubricant Capacity, pt (L) ............... 0.50 (0.24)
Clutch Housing Assembly Lubricant Capacity, pt (L) ............... 0.75 (0.35)

Service Intervals

Change engine oil ............... Every 50 hours
Inspect air cleaner ............... Every 8 hours
Service air cleaner ............... Every 50 hours
Clean fuel strainer ............... Every 100 hours
Valve clearance adjustment ............... Every 250 hours
Fuel system inspection ............... Every 100 hours
Clean spark plug ............... Every 100 hours
Replace spark plug ............... Every 300 hours
Clean cooling fin ............... Every 50 hours
Change reduction gear oil ............... Every 500 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 3.7500-3.7510 (95.250-95.275)
Cylinder Out of Round Wear Limit, in (mm) ............... 0.0030 (0.076)
Cylinder Taper Wear Re-bore Limit, in (mm) ............... 0.0040 (0.101)
Crankshaft Main Bearing Journal Diameter, in (mm) ............... 1.4990-1.5000 (38.074-38.100)
Crankshaft Journal Out of Round Limit, in (mm) ............... 0.0010 (0.025)
Connecting Rod Big End Journal Clearance, in (mm) ............... 0.0010-0.0025 (0.025-0.063)
Connecting Rod Side Play, in (mm) ............... 0.0080-0.0140 (0.203-0.355)
Crankshaft End Play, in (mm) ............... 0.0020-0.0050 (0.050-0.127)
Piston To Cylinder Wall Clearance, in (mm) ............... 0.0045-0.0060 (0.114-0.152)
Piston Pin Diameter, in (mm) ............... 0.8750-0.8754 (22.225-22.235)
Piston Pin To Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0005 (0.002-0.012)
Piston Pin To Connecting Rod Bushing Clearance, in (mm) ............... 0.0003-0.0007 (0.007-0.017)
Top Ring Groove Side Clearance, in (mm) ............... 0.0020-0.0035 (0.050-0.088)
Second Ring Groove Side Clearance, in (mm) ............... 0.0020-0.0035 (0.050-0.088)
Oil Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Top Ring End Gap, in (mm) ............... 0.0120-0.0220 (0.304-0.558)
Second Ring End Gap, in (mm) ............... 0.0120-0.0220 (0.304-0.558)
Oil Ring End Gap, in (mm) ............... 0.0100-0.0200 (0.254-0.508)
Cylinder Head Deck Flatness Rebuild, in (mm) ............... 0.0030 (0.076)
Intake Valve Head Diameter, in (mm) ............... 1.6250 (41.275)
Exhaust Valve Head Diameter, in (mm) ............... 1.3750 (34.925)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3725-0.3735 (9.461-9.486)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3710-0.3720 (9.423-9.448)
Intake Valve Stem To Guide Clearance, in (mm) ............... 0.0020-0.0040 (0.050-0.101)
Exhaust Valve Stem To Guide Clearance, in (mm) ............... 0.0035-0.0055 (0.088-0.139)
Valve Guide Inside Diameter, in (mm) ............... 0.3755-0.3765 (9.537-9.563)
Valve Face Angle, deg ............... 45.0
Valve Seat Angle, deg ............... 45.0
Valve Seat Contact Width, in (mm) ............... 0.0450-0.0600 (1.143-1.524)
Valve Spring Free Length, in (mm) ............... 1.8750 (47.625)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.1235-1.1245 (28.536-28.562)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 0.8735-0.8745 (22.186-22.212)
Camshaft Bearing Bore Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.088)
Camshaft End Play, in (mm) ............... 0.0040-0.0080 (0.101-0.203)
Cam Lobe Height (Intake), in (mm) ............... 0.2850 (7.239)
Cam Lobe Height (Exhaust), in (mm) ............... 0.2850 (7.239)

Tightening Torques

Cylinder Head Fasteners (1-Stage), lb-ft (Nm) ............... 15.00 (20.33)
Cylinder Head Fasteners (2-Stage), lb-ft (Nm) ............... 28.00 (37.96)
Cylinder Head Fasteners (3-Stage), lb-ft (Nm) ............... 38.00-42.00 (51.52-56.94)
Connecting Rod Cap Screws, lb-ft (Nm) ............... 22.00-26.00 (29.82-35.25)
Flywheel Retaining Center Nut, lb-ft (Nm) ............... 70.00-80.00 (94.90-108.46)
Crankcase Base Sump Mounting Bolts, lb-ft (Nm) ............... 24.00-28.00 (32.54-37.96)
Main Bearing Retaining Flange Cap Bolts, lb-ft (Nm) ............... 28.00-32.00 (37.96-43.38)
Camshaft Thrust Plate Fasteners, lb-ft (Nm) ............... 8.00-10.00 (10.84-13.55)
Spark Plug Installation, lb-ft (Nm) ............... 24.00-28.00 (32.54-37.96)
Intake Exhaust Manifold Stud Nuts, lb-ft (Nm) ............... 18.00-22.00 (24.40-29.82)
Governor Internal Weight Assembly Nuts, lb-ft (Nm) ............... 6.00-8.00 (8.13-10.84)
Governor Lever Arm Pinch Bolt Nut, lb-ft (Nm) ............... 7.00-9.00 (9.49-12.20)
Fuel Pump Crankcase Mounting Base Bolts, lb-ft (Nm) ............... 12.00-14.00 (16.26-18.98)
Carburetor Flange Intake Mounting Nuts, lb-ft (Nm) ............... 14.00-16.00 (18.98-21.69)
Air Shroud Panel Hardware Bolts, lb-ft (Nm) ............... 6.00-8.00 (8.13-10.84)
Starter Motor Frame Chassis Mounting Bolts, lb-ft (Nm) ............... 30.00-35.00 (40.67-47.45)
Starter Solenoid Electrical Lead Terminals, lb-ft (Nm) ............... 4.00-5.00 (5.42-6.77)
Flywheel Alternator Stator Ring Fasteners, lb-ft (Nm) ............... 5.00-7.00 (6.77-9.49)
Breather Valve Cover Assembly Screw, lb-ft (Nm) ............... 4.00-6.00 (5.42-8.13)
Crankcase Bottom Oil Drain Plug Fittings, lb-ft (Nm) ............... 20.00-24.00 (27.11-32.54)
Oil Inspection Dipstick Tube Adapter Fitting, lb-ft (Nm) ............... 15.00-18.00 (20.33-24.40)
Fuel Tank Secure Support Strap Anchors, lb-ft (Nm) ............... 8.00-10.00 (10.84-13.55)
Exhaust Pipe Locknut Canister Muffler Interface, lb-ft (Nm) ............... 35.00-45.00 (47.45-61.01)
Air Cleaner Mounting Flange Center Support Stud, lb-ft (Nm) ............... 5.00-7.00 (6.77-9.49)
Reduction Housing Cover Frame Bolts, lb-ft (Nm) ............... 22.00-26.00 (29.82-35.25)
Reduction Housing Oil Drain Plug Component, lb-ft (Nm) ............... 18.00-22.00 (24.40-29.82)
Clutch Assembly Hub Crankshaft Shaft, lb-ft (Nm) ............... 50.00-60.00 (67.79-81.34)
Clutch Pressure Plate Outer Cover Fasteners, lb-ft (Nm) ............... 18.00-22.00 (24.40-29.82)
Crankcase Breather Baffle Plate Internal Screw, lb-ft (Nm) ............... 3.00-5.00 (4.06-6.77)
Magneto Timer Outer Housing Attachment Screws, lb-ft (Nm) ............... 5.00-7.00 (6.77-9.49)

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• Wisconsin Engines Specs
  
• Wisconsin S7D Specs
  
• Wisconsin S8D Specs
  
• Wisconsin S10D Specs
  
• Wisconsin S12D Specs
  

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